Sept., :907 ] GiRAULT : TrICHOGRAMMA PRETIOSA RiLEY. 119 



Habits. — Although the parasites occur in great numbers, on 

 account of their minute size and inconspicuousness, they are rather 

 difficult to find in nature. For this reason their natural habits in 

 regard to activity are more or less unknown, except in the case of 

 ovipositing females. 



They have been observed crawling over the leaves of corn and 

 cotton, mostly in the morning of fair and clear days, but have never 

 been observed to feed on the secretions of leaf glands as do various of 

 the Chalcidoidea. In the laboratory, however, they have been fed on 

 ripe peach juice and a diluted water solution of brown sugar, some- 

 times feeding rather eagerly, but mostly quite incidentally, and in one 

 case, not at all. The taking of food seems to have no effect on the 

 length of life. 



In regard to the latter, of course, we have nothing but laboratory 

 records upon which to base conclusions. Through all of the breeding 

 season of 1904 numerous specimens were kept under spacious glass 

 jars, and their length of life noted. Summing up results, the average 

 length of life was about 36 hours or slightly longer, but the range was 

 from 12 to 108 hours. The longer period was very exceptional. The 

 males die somewhat earlier than the females. The season of the year 

 apparently has no effect on the length of life. Both sexes are very 

 active and crawl rapidly and they also fly and are then very hard to see. 



Percentage of Alabama eggs kitted. — A few records, late in the 

 season, were obtained for the percentage of the eggs of Alabama 

 aroillacea Hiibner, the cotton caterpillar, killed by this parasite. 

 On October 22, parasitized eggs were common on cotton but healthy 

 eggs scarce. Forty-six (46) eggs collected from the leaves on that 

 date showed by census 73.9 per cent, parasitism ; by the end of the 

 week following, the percentage for this lot was 76 per cent., another 

 egg having since shown the characteristic blackened color. 



The percentage oi obsoleta eggs parasitized during 1904 has been 

 given by Quaintance and Brues (1905). 



List of hosts. — The genus Trichogramma confines its attacks- 

 mostly to the Lepidoptera, as far as our records go, but one species,. 

 odontotcc Howard, attacking the Coleoptera ( Odontota dorsalis Thun- 

 berg), and one, ceresara Ashmead, known definitely to attack Hemip- 

 tera {Ceresa bubalus Fabr. ), and two species attacking the Hymen- 

 optera, namely, minuta Riley and pretiosa Riley. The latter species 

 is known to attack members of two orders, Hymenoptera and Lepidop- 



